JP2006303388A - Land of circuit mounting substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a land capable of suppressing the occurrence of position deviation at a position where a surface mount is bonded during the bonding of the surface mount on a circuit mounting substrate, and of solder bonding the surface mount accurately at a given position. <P>SOLUTION: The land 1L comprises a first land 11L and a second land 12L. The second land 12L comprises side surfaces 31a, 31b that are provided inward in the axial direction X of the first land 11L in integration with the first land 11L, and taper inward in the axial direction X. The side surfaces 31a, 31b are formed to straddle bottom side surfaces 41a, 41b of a chip resistor 3. Angles 42a to 42d on the inward side on the bottom face of electrodes 4L, 4R are all positioned inside the second lands 12L and 12R. The motion of the angle 42a both in the normal direction along the widthwide direction Y and in the normal direction along the widthwide direction X is physically limited by the side surface 31a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a land for a circuit mounting board, and in particular, when a surface mounting component is soldered to a circuit mounting board, the occurrence of displacement in the bonding position of the surface mounting component is suppressed, and the surface mounting component is placed in a predetermined position. The present invention relates to a land that can be soldered accurately.

  FIG. 7 is a plan view of a main part of the printed wiring board disclosed in Patent Document 1. As shown in FIG. As shown in FIG. 7, a pair of pads 102 are arranged on the printed wiring board 101 so as to face each other at a predetermined interval. A planar rectangular chip component 103 is placed on the pad 102. Both end portions of the chip component 103 are electrode portions 103a, and are electrically connected to the pads 102. The inner portion 102 a of the pad 102, that is, the inner side of the chip component 103, is formed so as to be narrow along the both sides of the chip component 103. On the other hand, the outer portion 102b of the pad 102, that is, the electrode portion 103a side of the chip component 103 is formed wider than the inner portion 102a of the pad 102, and suppresses misalignment during solder reflow.

In addition, there exists a technique currently disclosed by patent document 2 and 3 as another related technique.
JP-A-5-37144 Japanese Patent Laid-Open No. 7-212024 Japanese Patent Laid-Open No. 7-30238

  However, a gap having a width W101 exists outside the outer portion 102b in the axial direction. This is a problem because the chip component 103 may be displaced in the axial direction (left and right in the drawing) within the range of the width W101 during solder reflow. Another problem is that due to the occurrence of axial displacement, chip standing may occur due to different surface tensions of the reflowed solder at both electrode portions of the chip component 103.

  The present invention was made to solve the above-described problems of the prior art, and suppresses occurrence of displacement in the bonding position of the surface mounting component when the surface mounting component is soldered to the circuit mounting substrate, It is an object of the present invention to provide a land of a circuit mounting board capable of forming a fillet having a uniform and good shape by accurately soldering a surface mounting component at a predetermined position.

  To achieve the above object, a land according to claim 1 is a land of a circuit mounting board to which an electrode of a surface mount component is soldered, and the first land to which at least a part of the bottom surface of the electrode is soldered. And a second land portion that is provided integrally with the first land portion on the inner side in the axial direction of the surface mount component of the first land portion, and the width of the second land portion with respect to the axial direction is It changes along the inner side in the axial direction from the junction with the first land portion so as to be less than the width of the electrode across the edge in the width direction of the electrode from the width or more.

  The land of the circuit mounting board includes a first land portion and a second land portion. At least a part of the bottom surface of the electrode of the surface mount component is soldered to the first land portion. The second land portion is provided integrally with the first land portion inward in the axial direction of the surface mount component of the first land portion. The width of the second land portion with respect to the axial direction varies along the axial direction. The width of the second land portion changes from a value equal to or larger than the width of the electrode so as to be less than the width of the electrode across the edge in the width direction of the electrode. Therefore, at least one of the sides of the second land portion with respect to the axial direction of the surface-mounted component straddles the bottom side of the surface-mounted component. At this time, the side of the second land portion is provided with components in both the axial direction and the width direction.

  As seen from the bottom surface of the electrode, there are no lands in a region on the inner side in the axial direction from the side of the second land portion and a region on the outer side in the width direction. Here, since the solder does not get wet in the area where the land does not exist, there is no solder. In addition, the bottom surface of the electrode cannot move to a region where no solder exists. Then, the movement of the electrode bottom surface inward in the axial direction and outward in the width direction is physically restricted by the side of the second land portion.

  Thereby, the movement of the electrode in the axial direction and the width direction of the surface-mounted component can be physically restricted by the side of the second land portion. Therefore, since the surface-mounted component does not shift in the width direction, it is possible to form a good solder fillet having a uniform base in the width direction.

  Further, if a positional deviation in the width direction occurs when the surface mount component is placed, an area difference between the areas in the vicinity of both sides of the second land portion where the surface mount component does not exist is generated. And according to the said area difference, the difference of the surface tension of the reflowed solder generate | occur | produces. Then, a force that returns the position of the surface mount component to the center in the width direction acts on the surface mount component so as to eliminate the difference in surface tension. In particular, since the width in the width direction of the second land portion is narrower than the width in the width direction of the first land portion, the surface tension due to solder is difficult to disperse. Then, compared with the self-alignment effect obtained by the first land portion, the self-alignment effect obtained by the second land portion has an effect of moving the surface mounting component to the center in the width direction more accurately. . Thus, the surface-mounted component can be accurately soldered to the center position in the width direction by the self-alignment effect obtained by the second land portion.

  Further, since the second land portion is provided on the inner side in the axial direction, no limitation is imposed on the shape of the first land portion on the outer side in the axial direction. As a result, a free fillet shape can be formed outside the first land portion in the axial direction. For example, a land is secured in a region that is axially outward of the outer end surface of the electrode and outward in the width direction of the electrode, and a fillet is formed between the region and the outer end surface of the electrode. Can do. As a result, the stress relaxation effect of the fillet can be secured even in a surface-mounted component having no electrode on the side surface, and the crack resistance against the stress of the fillet can be increased.

  According to a second aspect of the present invention, in the land according to the first aspect, the lands are arranged so as to face each other according to the positions of the electrodes provided at both axial ends of the surface mount component.

  The lands having the second land portion are arranged to face each other. In the surface mount component, movement of the second land portion inward in the axial direction is restricted by one second land portion. Further, the movement of the second land portion inward in the axial direction is restricted by the other second land portion. Therefore, the movement of the electrode in the axial direction is restricted by each of the opposing second land portions. Thereby, generation | occurrence | production of position shift to the axial direction of surface mount components can be suppressed.

  The land according to claim 3 is the land according to claim 2, wherein the distance between the edges of the first land portion located on the inner side in the axial direction is the edge side located on the inner side in the axial direction of the electrode. The distance between the end sides of the second land portion that is located inward in the axial direction of the second land portion is equal to the distance between the end sides of the end sides that are present inward in the axial direction of the electrode. It is characterized by being made smaller than that.

  The width of the second land portion with respect to the axial direction changes so as to be less than the width of the electrode across the edge in the width direction of the electrode, before and after the change, when changing along the axial direction. . By having such a relationship between the distances between the end sides, both corners of the end sides existing inward in the axial direction of the electrode are located in the second land portion. Thereby, the movement of the corner | angular part of an electrode in the axial direction and the width direction can be restrict | limited by the side of a 2nd land part.

  The land according to claim 4 is characterized in that, in the land according to claim 1, the width of the second land portion with respect to the axial direction changes in a curved shape protruding outward in the axial direction. .

  Thereby, even when various stresses are applied to the facing portion between the land and the bottom surface of the electrode, it is possible to suppress stress concentration at both corners of the edge that exists inward in the axial direction of the electrode. Therefore, it becomes possible to increase the crack resistance of the solder joint portion against stress.

  The land according to claim 5 is characterized in that, in the land according to claim 1, the width of the second land portion in the axial direction changes linearly.

  Since the width of the second land portion with respect to the axial direction changes linearly, the side edge in the axial direction of the second land portion becomes narrower in a taper shape inward in the axial direction. Then, the side of the second land portion includes components in both the axial direction and the width direction of the surface mount component. As a result, the electrode bottom surface is physically restricted by the side of the second land portion from moving inward in the axial direction and outward in the width direction, and therefore it is possible to suppress the occurrence of displacement of the surface-mounted component. .

  The land according to claim 6 is a land of a circuit mounting board in which the electrodes of the surface mount component are soldered and are arranged to face each other according to the position of the electrode, and at least a part of the bottom surface of the electrode is soldered. A first land portion and a second land portion provided integrally with the first land portion in an axially inward direction of the surface mount component of the first land portion, the width of the second land portion with respect to the axial direction is The distance between the edges of the first land portion is narrower than the axial width of the first land portion and has a constant width, and the end-to-end distance existing inward in the axial direction of the second land portion is inward in the axial direction of the electrode. The distance between the edges of the first land provided in one land and the distance between the edges of the first land provided in the other land The edge-to-edge distance to the edge that exists in the direction is the edge of the edge that exists inward in the axial direction of the electrode. Characterized in that it is a between distance or more.

  The width of the second land portion is narrower than the width of the first land portion in the axial direction and has a constant value. Therefore, the shape of the second land portion is a shape that extends inward in the axial direction along the edge in the width direction of the electrode from the joint portion with the first land portion. Then, the axial side of the second land portion is arranged along the axial side of the electrode of the surface mount component. Then, as viewed from the bottom surface of the electrode, no land exists in the region outside in the width direction from the side of the second land portion, and the solder does not get wet. Therefore, the electrode bottom surface is physically restricted from moving outward in the width direction by the side of the second land portion.

  Further, the distance between the end sides of the second land portion that is located inward in the axial direction is defined as the distance between the second land portion end sides. Further, the distance between the end side existing in the axial direction of the second land portion provided in one land and the end side existing in the axial direction of the first land portion provided in the other land is set to The distance between the edges of the first land portion and the second land portion. In addition, the distance between the edge sides of the surface-mounted component that exists on the inner side in the axial direction of the electrode is defined as the distance between the electrode edge sides. The distance between the edges of the second land portion is set to a value equal to or smaller than the distance between the edges of the electrodes. The distance between the edges of the first land portion and the second land portion is greater than or equal to the distance between the electrode edge sides.

  As a result, the edge that exists in the axially inward direction of the second land portion is located at the position on the axially inward side from the edge that exists in the axially inward direction of the electrode of the surface mount component. It is arranged along. Then, when viewed from the electrode, there is no land in the region inward in the axial direction from the edge existing inward in the axial direction of the second land portion. Therefore, the movement of the bottom surface of the electrode in the axial direction is physically limited by the axially inner end side of the second land portion.

  Further, the distance between the first land portion-second land portion end sides is set to a value equal to or greater than the distance between the electrode end sides. Then, when the surface mount component has moved to the maximum in either of the axial directions (when moving to the position where the axially inner edge of the second land and the axially inner edge of the electrode interfere) In this case, at least a part of the electrodes of the surface mounting component on the moving direction side is present in the second land portion. Thereby, the movement of the electrode in the axial direction and the width direction can be physically restricted by the axially inner end side and the side side of the second land portion.

  According to the land of the circuit mounting board according to the present invention, when the surface mounting component is soldered to the circuit mounting board, it is possible to suppress the occurrence of displacement in the bonding position of the surface mounting component, and to place the surface mounting component in a predetermined position. Can be soldered accurately. Therefore, it is possible to form a solder fillet having a uniform and good shape and high crack resistance.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a circuit mounting board on which lands and surface mounting components of the circuit mounting board of the present invention are mounted will be described in detail below. FIG. 1 is a perspective view showing the relationship between lands and surface-mounted components. As shown in FIG. 1, a pair of lands 1 </ b> L and 1 </ b> R are disposed on the circuit mounting substrate 2 so as to face each other at a constant interval. A planar rectangular chip resistor 3 is placed on the lands 1L and 1R. Electrodes 4L and 4R are provided at both ends of the chip resistor 3, and are electrically connected to the lands 1L and 1R.

  The electrodes 4L and 4R of the chip resistor 3 are configured such that no electrode is present on the chip resistor side surface portion 5. Therefore, the electrodes 4L and 4R are formed in a substantially U-shaped longitudinal section. This is a configuration generally employed for chip resistors from the viewpoint of specifications and manufacturing of the chip resistor 3.

  FIG. 2 is a plan view showing the lands 1L and 1R. The lands 1L and 1R are arranged to face each other according to the positions of the electrodes 4L and 4R of the chip resistor 3. The land 1L includes a first land portion 11L and a second land portion 12L (shaded portion in the figure). The land 1R includes a first land portion 11R and a second land portion 12R (shaded portion in the figure).

  The left-right direction in FIG. 2 is the axial direction X of the chip resistor 3. Further, the vertical direction of the paper surface is defined as the width direction Y. In the land 1L, the second land portion 12L is provided integrally with the first land portion 11L inward in the axial direction X of the first land portion 11L. The width in the width direction Y of the second land portion 12L is the width W4 at the joint portion with the first land portion 11L, and the width W1 at the end side 30L in the axial direction X. Therefore, the width of the second land portion 12L with respect to the axial direction X changes from the width W4 to the width W1 inward in the axial direction X. Then, the second land portion 12 </ b> L includes side sides 31 a and 31 b that narrow in a tapered shape toward the inside in the axial direction X. Further, since the second land portion 12R in the land 1R has the same configuration, the description thereof is omitted here.

  FIG. 3 is a plan view showing the relationship between the lands 1L and 1R and the chip resistor 3. As shown in FIG. The electrode 4L has a width W2 in the width direction Y. In addition, the width W2 of the electrode 4L of the chip resistor 3 is wider than the width W1 of the second land portion 12 and narrower than the width W4. By having such a width relationship, the width of the second land portion 12L changes from the width W4 to the width W1 inward in the axial direction X so as to straddle the width W2. Further, the side 31a in the axial direction of the second land portion 12 is configured to straddle the bottom surface side 41a of the chip resistor 3, and the side 31b of the second land portion 12 is configured to cover the bottom surface side 41b of the chip resistor 3. It consists of straddles.

  A distance L1 is an end-to-end distance between the end side 32L existing in the axial direction X of the first land portion 11L and the end side 32R existing in the axial direction X of the first land portion 11R. Further, a distance L2 is an inter-edge distance between the end side 30L existing in the axial direction X of the second land portion 12L and the end side 30R existing in the axial direction X of the second land portion 12R. Further, the distance L3 between the end sides 34L existing in the axial direction X of the electrode 4L and the end side 34R existing in the axial direction X of the electrode 4R is defined as a distance L3. The distance L1 is made larger than the distance L3, and the distance L2 is made smaller than the distance L3. By having such a distance relationship, the inner corners 42a to 42d on the bottom surface of the electrode 4 are all located in the second land portions 12L and 12R. In the present embodiment, as shown in FIG. 3, the corner portions 42 a to 42 d are configured to be substantially in contact with the side edges 31 a to 31 d.

  The operation of the land according to the present invention will be described. First, a problem in a land that does not include the second land portion will be described with reference to FIG. The land 111L shown in FIG. 8A has a width W103 that is sufficiently wider than the width W102 of the electrode 104L. A region R101 (shaded portion in the figure) is provided at a position outward in the axial direction of the outer end face 106 of the electrode 104L and outward in the width direction of the electrode 104L. By providing the region R101, the solder fillet is formed from the outer end face 106 to the region R101 at the time of solder joining, so that the shape of the fillet skirt can be expanded in the width direction Y. There is an advantage that the crack resistance can be improved. However, the land 111L includes the region R101, so that the degree of freedom of movement of the chip resistor 113 in the width direction Y is high.

  During solder reflow, a difference in surface tension may occur due to various factors such as differences in the amount of solder, differences in position, and differences in how the temperature is applied in the reflow furnace. Then, as shown in FIG. 8A, there is a problem that the position of the chip resistor 113 may be displaced in the width direction Y due to the difference in surface tension during solder reflow. Further, if the area of the region R101 is reduced or the width W103 is reduced in order to suppress misalignment in the width direction Y, the shape of the bottom of the solder fillet cannot be expanded in the width direction Y. This is a problem because a significant stress relaxation effect may not be obtained.

  Further, another problem in a land that does not include the second land portion will be described with reference to FIG. The lands 111L and 111R have a sufficient area with respect to the outside in the axial direction X. This is to obtain a fillet having a sufficient stress relaxation effect by securing the length of the bottom of the solder fillet extending outward in the axial direction X from the electrodes 104L and 104R at the time of solder bonding. However, since the lands 111L and 111R have a sufficient area outside the axial direction X, the degree of freedom of movement of the chip resistor 113 in the axial direction X is high.

  Then, during solder reflow, the chip resistor 113 may be displaced in the axial direction X as shown in FIG. 8B due to the difference in surface tension of the solder. Further, when the positional deviation occurs in the axial direction X, there is a problem that chip standing (Manhattan phenomenon) may occur due to different surface tensions of reflowed solder in both electrode portions of the chip resistor 113.

  On the other hand, the effect of suppressing the displacement of the chip resistor 3 in the land having the second land portion according to the present embodiment will be described with reference to FIG. In FIG. 3, attention is paid to the relationship between the corner 42a on the bottom surface of the electrode 4L and the side 31a of the second land portion 12L. There are no lands in the positive direction of the width direction Y and the positive direction of the axial direction X when viewed from the corner 42a. Here, since the solder does not get wet in the area where the land does not exist, there is no solder. Further, the electrode 4L cannot move to a region where there is no solder. Then, the movement of the corner portion 42a in both the positive direction of the width direction Y and the positive direction of the axial direction X is physically restricted by the side 31a. Here, the movement in both the axial direction X and the width direction Y can be restricted because the side 31a has a tapered shape with an angle with respect to the axial direction X, so that the axial direction This is an effect obtained due to having the components of X and the width direction Y.

  Similarly, when attention is paid to the relationship between the corner portion 42b of the electrode 4L and the side 31b of the second land portion 12L, lands are present in the negative direction in the width direction Y and the positive direction in the axial direction X as viewed from the corner portion 42b. not exist. Accordingly, the corner portion 42b is physically restricted from moving in the negative direction in the width direction Y and the positive direction in the axial direction X by the side 31b.

  As described above, the movement of the electrode 4L in the positive and negative directions in the width direction Y is restricted by the side edges 31a and 31b of the second land portion 12L. That is, the movement of the electrode 4L in the width direction Y can be physically restricted by the second land portion 12L. Accordingly, since the chip resistor 3 is not displaced in the width direction Y, it is possible to form a good solder fillet having a uniform base in the width direction Y.

  Similarly, in the electrode 4R, the corner portion 42c of the electrode 4R is restricted from moving in the negative direction of the axial direction X by the side 31c having a taper. Further, the corner portion 42d is restricted from moving in the negative direction of the axial direction X by the side edge 31d. Then, the chip resistor 3 is restricted from moving in the positive direction of the axial direction X by the second land portion 12L, and is restricted from moving in the negative direction of the axial direction X by the second land portion 12R. The position of is completely fixed. That is, the land 1L including the second land portion 12L and the land 1R including the second land portion 12R are arranged to face each other, so that the movement of the chip resistor 3 in the axial direction X can be physically restricted. . Therefore, it is possible to form a good solder fillet having a uniform skirt in the axial direction X and to prevent the Manhattan phenomenon of the chip resistor 3 from occurring.

  The self-alignment effect in the land according to the present embodiment will be described. When the chip resistor 3 is placed at a predetermined position (FIG. 3) of the lands 1L and 1R using a mounter or the like, there is an error and it is difficult to place it completely at the center of the land. When the placement displacement in the width direction Y direction occurs, an area difference in a region where the chip resistor 3 does not exist is generated between the side 31a side and the 31b side of the second land portion 12L. And according to the said area difference, the difference of the surface tension of the reflowed solder generate | occur | produces. Then, a force to return the position of the chip resistor 3 to the center in the width direction Y acts on the chip resistor 3 so as to eliminate the difference in surface tension. This is a so-called self-alignment effect.

  Here, since the width (width W1, width W4) in the width direction Y of the second land portion 12L is narrower than the width (width W3) in the width direction Y of the first land portion 11L, the surface tension due to solder is dispersed. Hard to do. Then, compared with the self-alignment effect obtained by the first land portion 11L, the self-alignment effect obtained by the second land portion 12L has an effect of moving the chip resistor 3 more accurately to the center in the width direction Y. is doing. Thereby, by providing the second land portions 12L and 12R, the chip resistor 3 can be more accurately positioned at a predetermined position in the width direction Y. Therefore, it is possible to form a good solder fillet having a uniform base in the width direction Y.

  In addition, the advantage of the second land portion being provided not on the outer side in the axial direction X but on the inner side in the axial direction X will be described. First, as a comparison, the case where the second land portion is formed on the outer side in the axial direction X of the first land portion will be described with reference to FIG. The land 121L shown in FIG. 9 includes a second land portion 112L outside the axial direction X. The second land portion 112 </ b> L includes side sides 131 a and 131 b that are tapered in the axial direction X outward. The side sides 131a and 131b restrict the movement of the corners 142a and 142b on the bottom surface of the electrode 104L in the negative direction of the axial direction X. However, in the land 121L, since the sides 131a and 131b are formed, the region R100 (shaded portion in the drawing) is located at the outer side in the axial direction of the outer end face 106 of the electrode 104L and the outer side in the width direction of the electrode 104L. ). Therefore, a solder fillet cannot be formed between the outer end face 106 of the electrode 104L and the region R100. As a result, at the time of solder bonding of the chip resistor 113 having no electrode on the side surface of the chip resistor, a sufficient stress relaxation effect cannot be obtained, and the crack resistance of the solder fillet may be insufficient.

  However, in the present embodiment, as shown in FIG. 3, the second land portions 12L and 12R are provided on the inner side in the axial direction X of the first land portions 11L and 11R. Thereby, since the restriction | limiting is not imposed on the shape of the 1st land part 11L and 11R outside the axial direction X, the area | region R is securable. Therefore, a fillet can be formed in the region R, and a sufficient stress relaxation effect can be secured. Even in the chip resistor 3 having no electrode on the side surface, the crack resistance of the fillet can be increased.

  As described above in detail, in the land according to the first embodiment, the side sides 31a and 31b of the second land portion 12L have a tapered shape with an angle with respect to the bottom side sides 41a and 41b. Therefore, the movement of the corner portions 42a and 42b in the width direction Y is physically limited by the side edges 31a and 31b. As a result, the chip resistor 3 is not displaced in the width direction Y, so that it is possible to form a good solder fillet having a uniform base in the width direction Y.

  Further, the land 1L including the second land portion 12L and the second land portion 12R including the second land portion 12R are disposed to face each other. The chip resistor 3 is restricted from moving in the positive direction of the axial direction X by the second land portion 12L, and is restricted from moving in the negative direction of the axial direction X by the second land portion 12R. Accordingly, the electrode is restricted from moving in the axial direction X by the second land portions 12L and 12R, and positional deviation in the axial direction X can be suppressed. Further, the occurrence of chip standing due to the difference in surface tension of the reflowed solder between the two electrode portions of the chip resistor 3 can be prevented.

  Further, since the width in the width direction Y of the second land portions 12L and 12R is narrower than the width in the width direction of the first land portions 11L and 11R, the surface tension due to solder is not easily dispersed in the width direction Y. Then, the self-alignment effect obtained by the second land portions 12L and 12R moves the chip resistor 3 more accurately to the center in the width direction Y than the self-alignment effect obtained by the first land portions 11L and 11R. Has the effect of Thereby, the chip resistor 3 can be more accurately soldered to the center position in the width direction Y by the self-alignment effect obtained by the second land portions 12L and 12R.

  The second land portions 12L and 12R are provided on the inner side in the axial direction X. Therefore, no limitation is imposed on the shape of the first land portions 11L and 11R outside the axial direction X. As a result, a free solder fillet shape can be formed. In particular, a region R (a region outside the outer end surface of the electrode 4L and outside the electrode 4L in the width direction) is secured on the land, and a fillet is formed between the region R and the outer end surface of the electrode 4L. Can be formed. Even in the chip resistor 3 having no electrode on the side surface of the chip resistor, the crack resistance against the stress of the solder fillet can be increased.

  A second embodiment according to the present invention will be described with reference to FIG. FIG. 4 is a plan view showing lands 71L and 71R according to the second embodiment. The lands 71L and 71R are arranged to face each other according to the positions of the electrodes 4L and 4R of the chip resistor 3. The land 71L includes a first land portion 11L and a second land portion 72L. The land 71R includes a first land portion 11R and a second land portion 72R.

  The width W11 of the second land portion 72L is narrower than the width W13 of the first land portion 11L. The width of the second land portion 72L is constant at the width W11. Therefore, the shape of the second land portion 72L is a shape that extends inward in the axial direction X along the edge in the width direction of the electrode from the joint portion 73L with the first land portion 11L. Then, the side sides 81 a and 81 b in the axial direction of the second land portion 72 </ b> L are arranged along the side sides 84 a and 84 b in the axial direction on the bottom surface of the electrode 4 </ b> L of the chip resistor 3. Then, when viewed from the bottom surface of the electrode 4L, the second land portion 72L does not exist in the positive direction in the width direction Y from the side 81a of the second land portion and in the negative direction in the width direction Y from the side 81b. Solder does not get wet. Therefore, the electrode 4L is physically restricted from moving outward in the width direction Y by the side edges 81a and 81b of the second land portion 72L. Since the same applies to the second land portion 72R, the description thereof is omitted here.

  Further, the distance between the end sides 75L and 75R existing inward in the axial direction of the second land portions 72L and 72R is defined as a second land portion end side distance L13. Further, an end side 75L existing inward in the axial direction X of the second land portion 72L provided in the land 71L and an end side 76R existing inward in the axial direction X of the first land portion 11R provided in the land 71R. The distance is defined as a distance L12 between the first land portion and the second land portion end side. Further, the distance between the end sides of the end sides 34L and 34R existing inward in the axial direction X of the electrodes 4L and 4R is defined as an electrode end side distance L11. The distance L13 between the second land end sides is set to a value equal to or smaller than the electrode end side distance L11. The distance L12 between the first land portion and the second land portion end side is set to a value equal to or larger than the electrode end side distance L11.

  Therefore, the end side 75L existing in the axial direction X of the second land portion 72L is positioned on the inner side (positive direction) in the axial direction X from the end side 34L existing in the axial direction X on the bottom surface of the electrode 4L. Are arranged along the end side 34L. Then, when viewed from the bottom surface of the electrode 4L, the second land portion 72L does not exist in the positive region of the axial direction X from the end side 75L of the second land portion 72L. Therefore, the electrode 4L is physically restricted from moving inward (positive direction) in the axial direction X by the end side 75L of the second land portion 72L. Since the same applies to the second land portion 72R, the description thereof is omitted here.

  Further, by having the relationship between the distances between the edges, when the chip resistor 3 is moved to the maximum in the positive direction of the axial direction X (the edge 75L of the second land portion 72L and the edge 34L of the electrode 4L). In the case where the end 34R of the electrode 4R moves to a position where the two interfere with each other, the end 34R of the electrode 4R does not move in the positive direction of the axial direction X beyond the joint 73R. That is, at least a part of the bottom surface of the electrode 4R is necessarily present in the second land portion 72R. Therefore, even when the chip resistor 3 moves to the maximum in the positive direction of the axial direction X during solder reflow, the movement of the electrode 4R in the width direction Y is limited by the side edges 81c and 81d of the second land portion 72R. It is possible. The same applies to the action of the second land portion 72L when the chip resistor 3 is moved to the maximum in the negative direction of the axial direction X, and the description thereof is omitted here.

  As described above in detail, in the lands 71L and 71R according to the second embodiment, the lateral sides 81a to 81d of the second land portions 72L and 72R cause the electrodes 4L and 4R to move in the positive and negative directions in the width direction Y. Limited. Accordingly, since the chip resistor 3 is prevented from being displaced in the width direction Y, it is possible to form a good solder fillet having a uniform base in the width direction Y.

  The chip resistor 3 is restricted from moving in the positive direction of the axial direction X by the end side 75L of the second land portion 72L, and is restricted from moving in the negative direction of the axial direction X by the end side 75R of the second land portion 72R. Is done. Therefore, since the positional deviation of the chip resistor 3 in the axial direction X can be suppressed, the occurrence of chip standing can be prevented.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications can be made without departing from the spirit of the present invention. In the first embodiment, as shown in FIG. 3, the corner portions 42 a to 42 d are configured to substantially contact the side edges 31 a to 31 d, but the present invention is not limited to this configuration. The corners 42a to 42d only need to exist at positions on the outer side in the axial direction X with respect to the side edges 31a to 31d. The distance between the corners 42a to 42d and the sides 31a to 31d depends on the manufacturing yield of the circuit mounting board 2 including the lands 1L and 1R, the positioning accuracy of the mounter on which the chip resistor 3 is placed on the land, and the like. What is necessary is just to determine suitably. Here, the positioning accuracy of the chip resistor 3 can be increased as the distance between the corner and the side is designed closer. Further, as the distance between the corner portion and the side is designed to be increased, the manufacturing margin of the lands 1L and 1R and the positioning margin when the chip resistor 3 is placed become wider, and the cost reduction effect can be obtained.

  In the second embodiment, as shown in FIG. 4, in the positional relationship between the second land portion 72L and the electrode 4L, between the side 81a and the side 84a, between the side 81b and the side 84b, Although it is configured to have a predetermined amount of gap between the end side 75L and the end side 34L, it is not limited to this configuration. Needless to say, the second land portion 72L and the electrode 4L may have substantially the same side or end sides. As the gap is designed to be smaller, the positioning accuracy of the chip resistor 3 can be improved.

  In the first embodiment, as shown in FIG. 3, the lands 1L and 1R have the width W3. However, the present invention is not limited to this configuration. Like the lands 51L and 51R shown in FIG. 5, the chip resistor 3 may have a width W5 close to the width W2. Even in this case, the side edges 31a to 31d of the second land portions 12L and 12R prevent the chip resistor 3 from being displaced in the axial direction X and the width direction Y. Therefore, the chip resistor 3 can be positioned with higher accuracy.

  In the first embodiment, as shown in FIG. 3, the side edges 31a to 31d are linearly tapered. However, the present invention is not limited to this configuration, and the corner portions 42a to 42d of the electrodes 4L and 4R are physically formed. What is necessary is just the shape to regulate. For example, it is good also as a form which has an outward convex curvilinear shape and becomes narrow toward the inside of the axial direction X like the side 33a thru | or 33d of 2nd land part 52L and 52R shown in FIG. Thereby, even when various stresses are applied to the facing portions between the lands 61L and 61R and the bottom surfaces of the electrodes 4L and 4R, it is possible to prevent stress concentration on the corner portions 42a to 42d.

  Needless to say, the taper angles of the side edges 31a to 31d may be appropriately determined according to the mounting accuracy of the mounter. As an example, the side 31b (FIG. 3) will be described. Consider the angle of the side 31b with respect to the axial direction X. As the angle is 45 degrees as a boundary and larger than 45 degrees (approaching perpendicular to the axial direction X), the effect of suppressing the positional deviation in the axial direction X increases and the positional deviation in the width direction Y increases. The suppression effect is reduced. Therefore, the occurrence of chip standing can be more effectively prevented. On the other hand, as the angle is smaller than 45 degrees (approaching parallel to the axial direction X), the positional deviation suppressing effect in the width direction Y increases and the positional deviation suppressing effect in the axial direction X decreases. Therefore, in the case where the width direction Y of the lands 1L and 1R is expanded, the positional deviation of the chip resistor 3 in the width direction Y can be effectively suppressed.

  In this embodiment, the chip resistor is used as the surface mount component. However, the present invention is not limited to this, and it goes without saying that the present invention can be applied to various surface mount components such as a chip capacitor.

It is a perspective view which shows the relationship between a land and surface mount components. It is a top view showing land 1L and 1R concerning a 1st embodiment. 3 is a plan view showing a relationship between lands 1L and 1R and a chip resistor 3. FIG. It is a top view which shows land 71L, 71R which concerns on 2nd Embodiment. It is a top view which shows land 51L and 51R. It is a top view which shows the 2nd land parts 52L and 52R. 10 is a plan view of a principal part of a printed wiring board disclosed in Patent Document 1. FIG. It is a top view which shows the land which is not provided with a 2nd land part. It is a top view which shows the case where a 2nd land part is produced in the axial direction X outer side of a 1st land part.

Explanation of symbols

1L, 1R Land 2 Circuit mounting board 3 Chip resistor 4L, 4R Electrode 11L, 11R First land 12L, 12R Second land 31a to 31d Side 41a, 41b Bottom side 42a to 42d Corner

Claims (6)

The land of the circuit mounting board to which the electrodes of the surface mounting component are soldered,
A first land portion to which at least a part of the bottom surface of the electrode is soldered;
A second land portion provided integrally with the first land portion on an inner side in the axial direction of the surface mount component of the first land portion;
The width of the second land portion with respect to the axial direction is greater than the width of the electrode and less than the width of the electrode across the edge in the width direction of the electrode. A land characterized by changing along the axially inward direction.   2. The land according to claim 1, wherein the lands are arranged to face each other in accordance with positions of the electrodes provided at both ends of the surface-mount component in the axial direction. The distance between the side edges of the first land portion that is present inward in the axial direction is larger than the distance between the side edges of the edge that is present inward in the axial direction of the electrode;
The distance between the edges of the second land portion that is present inward in the axial direction is made smaller than the distance between the edges of the edges that are present inward in the axial direction of the electrode. The land according to claim 2, wherein   2. The land according to claim 1, wherein a width of the second land portion with respect to the axial direction changes in a curved shape protruding outward in the axial direction.   The land according to claim 1, wherein a width of the second land portion with respect to the axial direction changes linearly. The surface mounting component electrodes are solder-bonded, and are lands of a circuit mounting board that are arranged to face each other according to the position of the electrodes,
A first land portion to which at least a part of the bottom surface of the electrode is soldered;
A second land portion provided integrally with the first land portion on an inner side in the axial direction of the surface mount component of the first land portion;
The width of the second land portion with respect to the axial direction is narrower than the width of the first land portion with respect to the axial direction, and is a constant width.
The distance between the side edges of the second land portion that is present inward in the axial direction is equal to or less than the distance between the side edges of the edge that is present inward in the axial direction of the electrode.
An end side existing in the axial direction of the second land portion provided in one of the lands, and an end side existing in the axial direction of the first land portion provided in the other land. The land-to-end distance is equal to or greater than the end-to-end distance of the end side existing inward in the axial direction of the electrode.

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